• Interfacial leakage of elastomer seals at low temperatures 

      Akulichev, Anton; Echtermeyer, Andreas; Persson, B. N. J (Journal article; Peer reviewed, 2018)
      Interfacial leakage of air in hydrogenated nitrile butadiene rubber (HNBR) O-ring seals exposed to sub-ambient temperatures is studied. Flange-type fixtures with sealing surfaces produced by 3 different surface finish ...
    • Long Term Degradation of Polymers: Molecular and Macroscopic Effects 

      Berggren, Randi (Master thesis, 2013)
      Hydrolytic degradation in water at elevated temperatures is one of the most important reasons for failure in polymeric materials in offshore flexible risers. In this thesis the ageing of polyamide 11 (PA11) in deoxygenated ...
    • Long term material properties of pressure vessels made of composite material 

      Hugaas, Eivind (Doctoral theses at NTNU;2022:56, Doctoral thesis, 2022)
      Pressure vessels are currently the limiting factor in the hydrogen distribution chain. The pressure vessels are preferably made out of composite materials to achieve practical weight to strength ratios and avoid hydrogen ...
    • Long Term Properties of Glass Fiber Epoxy Laminates in Dry and Humid Environment 

      Hagen, William Eik (Master thesis, 2022)
      A study of the stress rupture time of glass fiber epoxy composite laminates in humid environments was investigated. Test specimens were made in order to compare the failure time of a saturated and non-saturated specimen ...
    • Long-Term Dissolution of Glass Fibers in Water Described by Dissolving Cylinder Zero-Order Kinetic Model: Mass Loss and Radius Reduction. 

      Krauklis, Andrey; Echtermeyer, Andreas (Journal article; Peer reviewed, 2018)
      Glass fibers are degraded when they are exposed to water. In this work, a model is developed that uses zero-order kinetics for predicting a decreasing glass fiber radius. The model is used to describe experimental test ...
    • Long-Term Hydrolytic Degradation of the Sizing-Rich Composite Interphase 

      Krauklis, Andrey; Gagani, Abedin; Echtermeyer, Andreas (Journal article; Peer reviewed, 2019)
      Glass fiber-reinforced composites are exposed to hydrolytic degradation in subsea and offshore applications. Fiber-matrix interphase degradation was observed after the matrix was fully saturated with water and typical water ...
    • Long-term ISO 23936-2 sweet oil ageing of HNBR 

      Akulichev, Anton; Alcock, Benjamin; Krauklis, Andrey; Tiwari, Avinash; Echtermeyer, Andreas (Journal article; Peer reviewed, 2021)
      A hydrogenated nitrile butadiene rubber (HNBR) compound is subjected to ageing in a simulated oil and gas environment in accordance with ISO 23936-2 standard at two elevated temperatures (130 °C and 150 °C) for a period ...
    • Long-Term Properties of Interlaminar Shear Strength of Composite Laminates 

      Monsås, Anna Birgitte (Master thesis, 2018)
      Components made of fiber reinforced polymers (FRP) are frequently used in environments with fluctuating temperatures and moisture levels. These environmental factors lead to a degradation of the FRP in the long term. The ...
    • Long-term properties of the matrix of composites 

      Næss, Christoffer (Master thesis, 2016)
      Water diffusion into epoxy can be looked upon on as a 3-stage process. The first stage is the initial reaction, where the ends and available surfaces of the molecular chains bond with the water molecules. These easily ...
    • Mechanical Properties of Elastomers at Low Temperatures for Sealing Applications 

      Vestre, Andreas (Master thesis, 2015)
      With increased oil and gas activity in low-temperature areas of the world, it is highly important that the industry utilize the most robust materials and zero-leakage solutions. The O ring is a type of elastomer sealer ...
    • Mechanical Properties of Elastomers at Low Temperatures for Sealing Applications 

      Vestre, Andreas (Master thesis, 2015)
      With increased oil and gas activity in low-temperature areas of the world, it is highly important that the industry utilize the most robust materials and zero-leakage solutions. The O ring is a type of elastomer sealer ...
    • Mechanism of Yellowing: Carbonyl Formation during Hygrothermal Aging in a Common Amine Epoxy 

      Krauklis, Andrejs; Echtermeyer, Andreas (Journal article; Peer reviewed, 2018)
      Epoxies are often exposed to water due to rain and humid air environments. Epoxy yellows during its service time under these conditions, even when protected from UV radiation. The material’s color is not regained upon ...
    • Micromechanical modeling of anisotropic water diffusion in glass fiber epoxy reinforced composites 

      Gagani, Abedin; Fan, Yiming; Muliana, Anastasia H; Echtermeyer, Andreas (Journal article; Peer reviewed, 2018)
      Fluid diffusion in fiber reinforced composites is typically anisotropic. Diffusivity in the fiber direction is faster than in the transverse direction. The reason for this behavior is not yet fully understood. In this work, ...
    • Modeling and Testing of Impact Damage in Composite Pressure Vessels 

      Skaar, Martin Welle (Master thesis, 2015)
      Composite pressure vessels are becoming widely used for transporting gas, lately also hydrogen. In order to enable extensive use of the pressure vessels, it is critical to ensure their societal acceptance, and thus safety ...
    • Modeling and testing of small diameter composite tubes under hydrostatic pressure 

      Dzubur, Emir (Master thesis, 2014)
      This thesis investigates the behavior of small diameter composite tubes that are exposed to external pressure. Composite tubes have a superior strength to weight ratio compared to steel tubes. The oil industry is facing ...
    • MODIFISERT PAKNING FOR ARKTISKE BETINGELSER 

      Nergård, Katrine Linnea (Master thesis, 2015)
      Arktis er anslått til holde verdens største gjenværende uutnyttede olje- og gassreserver. Oljesøl utgjør en enorm risiko for arktiske økosystemer. Som et resultat av dette at er et behov for forbedret tetningsteknolgi ...
    • MODIFISERT PAKNING FOR ARKTISKE BETINGELSER 

      Nergård, Katrine Linnea (Master thesis, 2015)
      Arktis er anslått til holde verdens største gjenværende uutnyttede olje- og gassreserver. Oljesøl utgjør en enorm risiko for arktiske økosystemer. Som et resultat av dette at er et behov for forbedret tetningsteknolgi ...
    • Multiscale Modelling of Environmental Degradation—First Steps 

      Echtermeyer, Andreas; Gagani, Abedin; Krauklis, Andrejs; Mazan, Tobiasz (Chapter, 2018)
      Fibre-reinforced plastics are praised for their good corrosion resistance. However, when this resistance needs to be documented for safety-critical applications extensive and time-consuming test programmes are needed. A ...
    • Near-Infrared Spectroscopic Method for Monitoring Water Content in Epoxy Resins and Fiber-Reinforced Composites 

      Krauklis, Andrejs; Gagani, Abedin; Echtermeyer, Andreas (Journal article; Peer reviewed, 2018)
      Monitoring water content and predicting the water-induced drop in strength of fiber-reinforced composites are of great importance for the oil and gas and marine industries. Fourier transform infrared (FTIR) spectroscopic ...
    • New end fitting based on bolted joints with composite tubes 

      Khentalov, Vadim Alexandrovich (Master thesis, 2015)
      This thesis contains work on joining the GFRP pipes with metal end fitting. Professor A. Echtermeyer have proposed a concept using bolted connections. Prior to my work Master students K.Dons and A. Fossaa have developed ...